Dyeing acrylonitrile polymers by applying an insoluble azo dyestuff and then heating



Patented Dec. 5, 1950 3,532.43"? mums AcaYILom'ramE "Permits" "BY 1 1 7 Claims.

7 This invention relates to an-improvedmethod of dyeing acrylonitrile polymers.

Considerable difilculty is encountered in dyeing the acrylonitrile polymers to deep, fast shades by the conventional dyeing processes; For ex-- ample, when fibers, yarns, fabrics, or other shaped articles comprising the acrylonitrilepolymers are treated with an aqueous dyebath containing a cellulose acetate type dyestufi (sometimes referred to as suspension or dispersal dyes,

i. e., insoluble anthraquinone and azo dyes which are applied to cellulose acetate from aqueous dispersion), in the conventional manner of dyeing cellulose acetate, the acrylonitrile polymer articles are merely tinted or dyed to extremely light shades. Moreover, the 'dyeings do not exhibit good fastness.

An object of the present invention is to provide an improved process for dyeing articles comprising an acrylonitrile polymer to deep, fast shades. Another object is to provide a process for dyeing the acrylonitrile polymers with a dyebathcomprising aqueous suspensions of certain azo dyestufls. A further object is to provide a method for dyeing the acrylonitrile polymers, which does not require the use of special dyeing assistants comprising swelling agents or solvents for the polymer. Other objects will appear hereinafter. I have found that the articles comprising acrylonitrile polymers can be colored by the dyestuffs aforementioned and that the depth of shade and fastness of the dyeings obtained can be markedly improved if, subsequent to the dyeing operation and drying of the dyed article, the article is heated at an elevated temperature of from 120 to a 125 C., for at least one hour.

The dyestuffs which are useful in dyeing the acrylonitrile polymers comprise azo aniline derivatives as set forth in the example.

The article comprising the acrylonitrile polymer is treated with the dyebath in the usual manner, using various quantities of dyestufi, with different dyebath ratios and-temperatures of the bath, depending on th polymer being dyed, and after the dyeing operation, the article is dried and then baked, as previously explained. The baking to which the dyed article is subjected in the after-treating step serves to fix the dyestuff and results in a marked improvement in the extent of penetration of the dye through the article as evidenced by examination of the cross-section, in the intensity of the color, and in the fastness. The articles dyed and after-treated in accordance with this invention are superior to the control, that is, an acrylonitrile polymer article ,dyed in a dyebathoi the same composition, under the same conditions, but whichiisi notsublected to the baking afteretreatment.

, The following ,e'ik'ample is ;--i11ustrtiye$ offline invention: I -"Ezample Different lots 6: yarns 611. a haematit -i 6- nitrile and vinyl chloride containing"44 mol per cent a rylonitrile .in'the polymer inlolecule ,weie

dyed in different baths having a. dycbath, ratio or 1:30 and each containing 2% by weightof one of the dyestuffs listed below, each lot or yarn L being treated with one of thebaths.

Benzeneazoem-phenylenediamine L p-Dimethylamino azoxbenzene l p-Nitro benzene azo-B-hydroxyethyl aniline H p-Nitro benzene"azo fi-hydroxyethy1eethylaniline -p-Nitro benzene .azo-fi-hydroxyethyl-methylaniline I p-Nitro benzene azo-phydroxyethyko-toluidine p-Nitro benzene azo-di(fi-hydroxyethyl) -anili'ne p-Nitro benzene azo'dimethylaniline 2-methoxy-4-nitro benzene azoep-hydroxyethyl aniline 2-methoxy-4-nitro methylaniline 2-methoxy-4-nitro o-toluidin 2-methoxy-4-nitro benzene azo-p-hydroxyethyl benzene azo-p-hydroxi'ethyl benzene m-toluidine 2-methoxy-4-nitro benzene azo dimethylanillne 2,4-dinitro benzene azo-fi-hydroxyethyl aniline 2,4-dinitro benzene azo-prhydroxyethyl-ethylaniline 2,4-dinitro' benzene a zo fi-hydroxyethyhmethylaniline 1 2,4-dinitro benzene azo-p-hydroxyethyl o-tolui- ,dine.

. dine 2,4-dihitro benzene azo dimethylaniline.

m-Nitrobenzene azo-fi-hydroxyethyl aniline O-methoxy benzene azo-fl-hydroxyethyl aniline 2,6-dichlor-4-nitro benzene azo-fl-hydroxyethylmethylaniline oven at 120-125 C. for at least one hour. and preferably for about four hours. After the baking treatment the yarns had an intense color and fastness to fading greatly superior to the depth of shade and fastness oi the dyed air-dried yarns. prior to the baking after-treatment.

The method of improving the depth of shade and fastness of the dyeing by subjecting the dried, dyed article to the baking treatment appears to be specific to articles comprising polymers containing acrylonitrile in the molecule which have been dyed by means of the particular azo derivatives disclosed herein. Baking did not improve either the depth of shade or the fastness in acrylonitrile polymer articles dyed with other dyestuifs of the type commonly applied to cellulose acetate, and the examination of the crosssection of such articles before and after the baking step did not show improved penetration of the dye as a result of the baking.

The article to be dyed may comprise the acrylonitrile polymer in the form of fibers, yarns, fabrics, filaments, foils, rods, tubings and other shaped articles. The dyeing and baking may be performed on a batch or continuous basis. For example, yarns may be passed continuously through the dyeing, rinsing, scouring, drying, and baking stages and treated on the run, or the article in bulk, for example yarns in skein or other packaged condition, may be treated with the dyebath and then after withdrawal from the dyebath, subjected to the baking step.

While various embodiments of the invention have been described in detail for the purpose of illustrating the invention, it is to be understood that changes and variations may be made in practicing the invention, for example in the composition of the acrylonitrile polymer, the concentration of the dye in the bath, etc., without departing from the spirit and scope of the invention as defined in the appended claims.

Iclaim:

1. A method of dyeing shaped articles comprising an acrylonitrile polymer which comprises treating the article with an aqueous dyebath containing a water-insoluble azo dyestufl selected from the group consisting of Benzene azo-m-phenylenediamine p-Dimethyl amino azo benzene p-Nitro benzene azo-fi-hydroxyethyl aniline p-Nitro benzene azo-p-hydroxyethyl-ethylaniline p-Nitro benzene azo-p-hydroxyethyl-methylaniline p-Nitro benzene azo-fi -hydroxyethyl-o-toluidine p-Nitro benzene azo-di(fihydroxyethyl) -aniline p-Nitro benzene azo dimethylaniline 2-methoxy-4-nitro benzene azo-fi-hydroxyethyl aniline 2-methoxy-4-nitro benzene azo-p-hydroxyethyl methylaniline 2-methoxy-4-nitro benzene azo p hydroxyethyl o-toluidine drying the dyed article, and thereafter heating the article at a temperature of from to 0., for at least one hour.

2. A method as in claim 1 in which the article comprises a copolymer of acrylonitrile and vinyl chloride.

3. A method asin claim 1 in which the dye-' stufl is p-dimethylamino azobenzene.

4.A method as in claim 1 in which the dyestufl is p-nitrobenzene azo-p-hydroxyethyl aniline.

5. A method as in claim 1 in which the dyestuil' is p-nitrobenzene azo-p-hydroxyethyl ethylaniline.

6. A method as in claim 1 in which the dyestuif is 2-methoxy-4-nitrobenzeneazo-fi-hydroxyethyl aniline.

7. A method as in claim 1 in which the dyestuif is 2,4-dinitrobenzeneazo-p-hydroxyethyl aniline.

RALPH B. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name. Date 2,080,254 Dreyfus May 1, 1937 2,359,735 Kienle Oct. 10, 1944 2,461,612 Olpin Feb. 15, 1949 FOREIGN PATENTS Number Country Date 568,037 Great Britain Mar. 15, 1945 OTHER REFERENCES Amer. Dye. Reporter for October 27, 1941, pp. 575, 578 (article by Heymann) Rayon and Synth. Textiles for September 1948, pp. 107, 108 (article by Field).

Amer. Dyes Rep. for April 22, 1946, pp. p194, p195. 

1. A METHOD OF DYEIG SHAPED ARTICLES COMPRISING OF ACRYLONITRILE POLYMER WHICH COMPRISES TREATING THE ARTICLE WITH AN AQUEOUS DYEBATH CONTAINING A WATER-INSOLUBLE AZO DYESTUFF SELECTED FROM THE GROUP CONSISITNG OF 